cors.go

package auth

import (
	"regexp"
	"strings"
	"time"

	"github.com/gin-contrib/cors"
	"github.com/gotify/server/v2/config"
)

// CorsConfig generates a config to use in gin cors middleware based on server configuration.
func CorsConfig(conf *config.Configuration) cors.Config {
	corsConf := cors.Config{
		MaxAge:                 12 * time.Hour,
		AllowBrowserExtensions: true,
	}
	compiledOrigins := compileAllowedCORSOrigins(conf.Server.Cors.AllowOrigins)
	corsConf.AllowMethods = conf.Server.Cors.AllowMethods
	corsConf.AllowHeaders = conf.Server.Cors.AllowHeaders
	corsConf.AllowOriginFunc = func(origin string) bool {
		for _, compiledOrigin := range compiledOrigins {
			if compiledOrigin.MatchString(strings.ToLower(origin)) {
				return true
			}
		}
		return false
	}
	if allowedOrigin := headerIgnoreCase(conf, "access-control-allow-origin"); allowedOrigin != "" && len(compiledOrigins) == 0 {
		corsConf.AllowOrigins = append(corsConf.AllowOrigins, allowedOrigin)
	}

	return corsConf
}

func headerIgnoreCase(conf *config.Configuration, search string) (value string) {
	for key, value := range conf.Server.ResponseHeaders {
		if strings.ToLower(key) == search {
			return value
		}
	}
	return ""
}

func compileAllowedCORSOrigins(allowedOrigins []string) []*regexp.Regexp {
	var compiledAllowedOrigins []*regexp.Regexp
	for _, origin := range allowedOrigins {
		compiledAllowedOrigins = append(compiledAllowedOrigins, regexp.MustCompile(origin))
	}

	return compiledAllowedOrigins
}